1. Field of the Invention
This invention relates to a wind-up mechanism for a camera, and more particularly to a film wind-up device for a photographic camera.
2. Description of the Prior Art
In the conventional film wind-up mechanism, the wind-up shaft is provided with a wind-up lever secured to the upper end thereof, a film take-up spool rotatably mounted on the intermediate portion thereof, and a drive gear secured to the lower portion thereof for charging a shutter mechanism. The film wind-up shaft is generally rotated by 120.degree. to 180.degree.. The rotation of the wind-up shaft is transmitted to the spool gear through a rachet mechanism and gear train. The spool gear and the take-up spool are friction coupled to each other so that the take-up spool is rotated by about 360.degree. to wind up one frame of the film upon drive of the spool gear. On the other hand, the drive gear for charging the shutter is secured to the lower portion of the film wind-up shaft and is rotated 120.degree. to 180.degree. together with the wind-up lever to charge the shutter.
In the above mentioned wind-up mechanism, the spool gear and the take-up spool are freely mounted on the wind-up shaft and a friction plate is interposed between the spool gear and the take-up spool. Therefore, while the wind-up shaft is rotated 120.degree. to 180.degree., the spool gear and the take-up spool are rotated about 360.degree., and accordingly slippage occurs therebetween and a large torque for winding up the lever is needed. Particularly when the film wind-up shaft and the take-up spool are rotated in the opposite directions, the above drawbacks becomes prominent.